Lubricant compositions



United States PatentG 3,077,451 LUBRICANT COMPOSITEGNS Morton Antler, Detroit, Mich, assignor to Ethyl Corporation, New York, N.Y., a corporation of Virginia No Drawing. Filed Aug. 1, 1953, Ser. No. 752,414 6 Claims. (Cl. 252-464) This invention relates to novel compositions comprising dialkyl-tin sulfide compounds admixed with a hydrocarbon base oil or grease.

In the compounding of functional fluids, it is common practice to use various additives to impart certain desirable characteristics to the fluids. Thus, there are additives which impart antioxidant properties to fluids, additives which impart anti-wear characteristics to fluids, and additives which promote the use of fluids as cutting oils. In general, the function of an additive is specific so that it perform but one function. In exceptional cases an additive may perform a variety of functions, such as an anti-wear as well as an antioxidant function. It is obvious that a multi-functional additive is desirable since its use requires the blending of only one additive in the base fluid and eliminates any possibility of an inhibiting effect by one additive upon another additive in the same system.

Fluids which are used in lubricating systems operating at extreme pressures and temperatures are subjected to very severe conditions. In the presence of oxygen, these fluids tend to oxidize, thus forming decomposition products which inhibit the lubricating effect of the fluid. Further, the fluids are subjected to high shear forces which tend to force the lubricant film from between the rubbing members so that effective lubrication is not obtained. Lubricants or fluids presently used in extreme pressure lubrication contain additives which corrode the rubbing surfaces so as to form corrosion films on the surfaces, which films act as a lubricant. Such additives are termed extreme pressure (E.P.) additives.

The El. additives presently used have a number of drawbacks as for example:

(1) They, in general, have no antioxidant effect upon the lubricant base fluid.

(2) The mechanism by which they function involves sacrificial corrosion of the rubbing surfaces.

(3) Their corrosion mechanism is ineffective in lubricating non-reactive rubbing surfaces.

A typical example of, a commonly-used E.P. additive is carbfon tetrachloride. This additive, when used in lubricating a ferrous surface, breaks down in the lubrication system to form degradation products which react with the surface iron oxide coating to form a film of ferrous chloride. The ferrous chloride film then acts as a lubricant between the rubbing surfaces. Such an additive has little or no lubricating effect in a rubbing system in which the rubbing members are relatively nonreactive and resist corrosion. Typical examples of such relatively non-reactive rubbing systems are titanium-ontitanium, stainless steel-on-stainless steel, and gold-ongold. Other typical non-reactive materials are plastics, such as nylon, polyinethyl methacrylate, polyvinyl chloride, and polyethylene and hard refractory ceramic materials, such as tungsten carbide, aluminum oxide, silicon carbide and glass.

Rubbing systems may have relatively non-reactive surfaces for several reasons. Firstly, the rubbing members may be composed of an inert material, such as gold which is essentially inert to any chemical reaction. Secondly,

3,fl77,45l Patented Feb. 12, 1963 the rubbing members may have a tenacious oxide film which is non-reactive. Such a case is presented by titanium which forms a tenacious surface oxide coating which is extremely non-reactive. It must be understood, however, there are many applications for which E.P. additives have no suitable substitutes. Such is the case in cutting oils in which the El. additive lubricates the interface between the cutting tool and the work through a corrosion mechanism.

It is a general object of this invention to provide hydrocarbon base materials having superior antioxidant qualities, anti-wear qualities under all conditions, and having great utility as cutting oils. A more particular object is to provide said hydrocarbon materials by the use of a single additive which is multi-functional in its operation. A further object is to provide hydrocarbon base lubricant compositions which areefi ective in lubricating relatively non-reactive rubbing surfaces operating under extreme conditions. Another object is to provide hydrocarbon base lubricant compositions which are ex.- tremely effective cutting oils and are oxidatively stable. Additional objects of this invention will become apparent from the description and claims which follow.

In the accomplishment of the above objects, it has been found that the lubricity, antioxidant properties, and cutting oil utility of hydrocarbon base lubricants may be greatly enhanced by. adding thereto certain dialkyltin sulfide compounds. These compounds are generally employed in a concentration sufficient to increase the lubricity of the hydrocarbon base material. In eflec'ting lubrication, these additives are believed to function in two ways. First they may act as film formers in which the additive is degraded by the effect of heat and pressure generated by the rubbing surfaces. This degradation results in the formation of a film on the rubbing members, which film is formed entirely from the addi tive. Thus, the additive enables effective lubrication of rubbing members which are relatively non-reactive and resist corrosion by a conventional E.P. additive. Secondly, the additive may also function through a corrosion mechanism in the manner of a conventional E;-P.; additive. Thus, the additive enables the formation of extremely effective cutting fluids which use a corrosion mechanism in lubricating the contact surface between the cutting tool and the work. 7

Because of the dual manner in which my lubricant additives can function, they are versatile over a wide concentration range in a hydrocarbon base lubricant material. In lubricant compositions they may be employed over the concentration range of from about 0.05 percent by weight to about 10 percent by weight. They may be used at higher concentrations in lubricants if desired. Generally, however, such use is not justified because of the high cost of the additive. Thus, the upper limit of 10 percent is fixed primarily by economic factors rather than technical reasons.

In cutting oil formulations, the additive may be present in a much higher concentration thanin the case of a lubricant formulation. The very extreme conditions encountered in cutting require a heavily-dopedfluid. In this application the economic factor of high cost of the additive is completely outweighed by the technical requirements for the cutting fluid. Thus, when formulating a cutting fluid, the dialkyl-tin sulfide additive is used over a concentration range of. from 10 percent to about percent by weight. The demarcation line of 10 percent between lubricant and cutting oil formulations is a not a sharp one. Thus, because of the changing economic conditions resulting at decreased prices of dialkyltin sulfide compounds, it may be desirable to employ concentrations greater than 10 percent in lubricant formulations.

The dialkyl-tin sulfide compounds employed in forming my fluid compositions have the following structural formula in which R and R may be the same or different alkyl groups and contain from 3 to 6 carbon atoms. As illustrative examples of these compounds, there are di-npropyl tin sulfide, di-n-butyi tin sulfide, diisopropyl tin sulfide, di-n-pentyl tin sulfide, di-n-hexyl tin sulfide, n-propyl-n-hexyl tin sulfide, Z-Sec-Vpentyl isopropyl tin sulfide, and the various positional isomers thereof.

The dialkyl tin sulfide compounds, as set forth above, having straight-chain hydrocarbon substituent groups are generally more stable than are their branched chain counterparts. Thus, the straight-chain members are preferred in forming the hydrocarbon base materials of my invention. A further preferred embodiment of my invention is hydrocarbon base materials containing di-n-butyl tin sulfide. Such compositions are found to have most excellent anti-wear properties, antioxidant properties, and cutting oil properties over a wide load range under extreme operating conditions.

The specified dialkyl tin sulfide compounds may be easily prepared by known processes. As an example, an alkyl bromine compound such as propyl bromide may be reacted with a tin-zinc-sodium alloy containing an excess of sodium. This reaction results in the preparation of a tetraalkyl tin compound as for example tetrapropyl tin. The tetraalkyl tin compound is then halogenated, as for example with bromine or iodine, to form a dialkyl tin dihalide such as dipropyl tin dibromide. The dialkyl tin dihalide compound may then be reacted with an alkali sulfide compound such as sodium sulfide in the presence of heat and a suitable solvent to form the dialkyl tin sulfide compound. A suitable solvent for the reaction of sodium sulfide and di-n-propyl tin dibromide is ethyl alcohol. This reaction will go smoothly, when heated, to prepare di-n-propyl tin sulfide.

In formulating lubricant compositions within the scope of my invention, the hydrocarbon base material can be any hydrocarbon known in the art as a lubricant. Thus, it can be derived from various sources, such as animal, vegetable or mineral oil stocks and can be either in the form of an oil or a grease.

If the hydrocarbon base lubricant material is an oil, it is preferred to use mineral lubricating oil having a viscosity corresponding to Society of Automotive Engineers classification SAE W through SAE 50. This classification or crankcase oil, adopted in 1950, is as follows:

SAE viscosity No.:

SAE 5W 4000 sec. at 0 F. max.

(see Note C). SAE 10W 6000 to 12,000 sec. at 0 F.

(see Note A). SAE 20W 12,000 to 48,000 sec. at 0 F.

(see Note B). SAE 20 45 to 58 sec. at 210 F. SAE 30 58 to 70 sec. at 210 F. SAE 40 70 to 85 sec. at 210 F. SAE 50 85 to 110 sec. at 210 F.

No'rn A.Minimum viscosity at 0 F. of the low grade can be waived provided the viscosity at 210 F. is not below 40 seconds Saybolt.

NOTE B.\1inimum viscosity at 0 F. of the 20W grade can be waived provided the'viscosity at 210 F. is not below 45 seconds Saybolt.

No'ru C.The viscosity of oils included in this classification for use in crankcases shall not be less than 39 seconds Saybolt at 210 F.

The hydrocarbon base greases which may be utilized in forming lubricant compositions suitable for use in the present method are complex semi-solid or solid combinations of a petroleum product and a soap or a mixture of soaps with or without fillers. The primary components of the grease are soaps and mineral oils. Such soaps may be derived from animal or vegetable fats or fatty acids, wool grease, rosin, or petroleum acids. Typical examples of such soaps are lead oleate, lithium stearate, aluminum tristearate, lithium naphthenate, barium oleate, strontium stearate, lead naphthenate and the like. A preferred class of greases are those prepared from lithium or calcium soaps and mineral oil.

The mineral oil may consist of varying proportions of parafiinic, naphthenic and aromatic hydrocarbons. In addition, any or several of the following components may be present in the lubricating grease: unreacted fat, fatty acids, and alkali; unsaponifiable matter, including glycerol and fatty alcohols; rosin or wool grease; water; and certain additives which may function as modifiers or peptizers. Some of the materials listed may enter as impurities, remaining from incomplete reactions of the soap ingredients, or may be added purposely to stabilize or modify the structure It is evident that most lubricating greases contain a varied mixture of components. The use of ingredients, such as fats and lubricating oils, each of which consists of a number of chemical compounds, was originally limited to a large extent by economic factors and availability. Subsequent empirical results have, in the main, justified their usage. Grease compounding remains, however, largely an empirical science. With the wide diversity of compounding ingredients utilized in formulating a single grease, it is very difficult if not impossible to predict physical and chemical characteristics of the grease solely on the basis of theory.

To further illustrate my invention, as applied to lubricating compositions, there are presented the following examples which show typical lubricant compositions within the scope of my invention. Unless otherwise specified, proportions given in these examples are on a weight basis.

EXAMPLE I Five parts of di-n-butyl tin sulfide were blended with parts of a parafiinic, mineral white oil having a sulfur content of 0.07 percent, a kinematic viscosity (ASTM D 445) of 17.15 centistokes at F. and 3.64 centistokes at 210 F. Its viscosity index (ASTM D 567) is 107.5.

EXAMPLE II To 99.9 parts of a phenol-treated, mixed-base mineral oil having a viscosity of 307 SUS at 100 F. and 53.4 SUS at 210 F. and having a viscosity index of 103 is added 0.1 part of di-n-hexyl tin sulfide.

EXAMPLE IV Five parts of di-n-propyl tin sulfide are blended with 95 parts of Mid-Continent, solvent-extracted, propane-dewaxed mineral oil having a sulfur content of 0.17 percent and a viscosity index of approximately 95.

EXAMPLE V Four parts. of di-n-pentyl tin sulfide are blended with 96 parts of a solvent-extracted Pennsylvania bright stock having a Saybolt viscosity at 100 F. of 666 and a Saybolt viscosity of 76.0 at 210 F., a viscosity index of 107 and an aniline point of 116.0" C.

EXAMPLE VI A mixture of 13.8 parts of lithium stearate, 1.7 parts of calcium steara-te, 33.8 parts of a California solvent refined, parafii'nic base oil having a viscosity of 356 SUS at 100 F. and 50.7 parts of a California solvent-refined, paraffinic base oil having a viscosity of 98 SUS at 100 F. is heated to 425 F. for a period of 15 minutes. The mixture is cooled to room temperature and milled. To this mixture are added and mixed 0.05 part of n-butyl-n-hexyl tin sulfide.

EXAMPLE VII To 90 parts of a grease consisting of 15 percent of a soda soap prepared from equal amounts of stearic acid and of rosin, 10 percent of candelilla wax and 75 percent of mineral lubricating oil of a viscosity of 100 SUS at 210 F. and a viscosity index of 72 are added and mixed 10 parts of di-n-pentyl tin sulfide.

EXAMPLE VIII Ten parts of di-n-butyl tin sulfide are blended with the mineral oil utilized in Example I.

EXAMPLE XIX To 95 parts of a lead soap-containing grease consisting of 1.17 par-ts of litharge, 2.94 parts of hydrogenated fish oil fatty acids, 40 parts of blown asphalt, 25 parts of mineral oil of 180 SUS at 210 F., and 31 parts of oil of 125 SUS at 100 F. are added and mixed parts of (ll-li-blltYl tin sulfide.

EXAMPLE X To 99.9 parts of the mineral oil utilized in Example I was added 0.1 part of di-n-butyl tin sulfide.

Numerous of my lubricant compositions comprising a dialkyl-tin sulfide compound admixed with hydrocarbon base material as defined above were tested in a four-ball lubricant test machine to determine the lubricating effectiveness of the respective compositions under various test conditions. Two types of four-ball lubricant test machines were used in these tests. They are the Extreme Pressure Lubricant Tester (hereinafter referred to as the E.P. tester) and the Four-Ball Wear Machine. The E.P. tester is described by Boerlage in Engineering, volume 136, July 14, 1933, pp. 46.47. The Four-Ball Wear Machine is described by Larsen and Perry in the Transactions of the A.S.M.E., January 1945, pp. 45-50.

The two types of four-ball lubricant test machines are essentially the same in principle of operation and difier only in their load ranges. The E.P. tester operates in the range of to 800 kilograms and the Four-Ball Wear Machine operates in the load range of 0.1 to 50 kilograms. The Four-Ball Wear Machine differs from the E.P. tester in that it is more sensitive and can measure loads to a tenth of a kilogram, whereas the E.P. tester is not accurate in measuring load increments of less than 1 kilogram.

Both types of four-ball lubricant wear machines utilize four balls of equal size, arranged in a tetrahedral formation. The bottom three balls are held in a nonrotatable fixture which is essentially a universal chuck that holds the balls in abutting relation to each other. Since the bottom three balls are of equal size, their centers form the apices of an equilateral triangle. The top ball is afiixed to a rotatable spindle whose axis is positioned perpendicularly to the plane of the non-rotatable fixture and in line with the center point of the triangle whose apices are the centers of the three bottom balls.

In operation, the four balls are immersed in the lubri cant composition to be tested and the fixture holding the three bottom balls is moved upwardly so as to bring the three fixed balls into engagement with the upper rolling ball. To increase the load, the fixture is moved upwardly and axially of the rotating spindle afiixed to the upper ball.

The lubricating effectiveness of the lubricant is determined by the amount of wear occurring on the lower balls at their points of contact with the upper rotating ball. If the lubricant proves completely effective, the amount of wear will be negligible. If the lubricant is not completely effective, the upper ball may weld or seize to the lower balls. Such failure is due to the heat of friction generated at the contact points between the balls. A less severe type of failure is manifested by the occurrence of excessive wear in the absence of seizure or welding of the balls. In some cases the average diameter of the circular scar areas formed on the lower balls is measured. Such measurement gives a quantitative basis for comparing the lubricating effectiveness of a lubricant under one set of test conditions with its lubricating effectiveness under a second set of test conditions. As the severity of the test conditions is increased and higher loads are applied, the magnitude of wear and the likelihood of seizure or welding is increased.

A series of tests was conducted in the Four-Ball Wear Machine. In these tests my lubricant compositions of the type set forth in Examples I through X were tested to determine their lubricating efiectiveness relative to a non-additive-containing hydrocarbon base lubricating oil. The general test conditions were the same in each of the tests with the four balls being one-half inch in diameter and constructed of SAE 52-100 steel. The speed of rotation of the upper ball was 572 rpm. and the temperature of the lubricant was maintained constant at 50 C.

In order to establish a base line for comparison, a non-additive-containing parafiinic, white mineral oil having a sulfur content of 0.07 percent, a kinematic viscosity (ASTM D 445) of 17.15 centistokes at F., and 3.64 centist okes at 210 F. was tested at a number of loads. Each test was run for two hours after which the balls were disassembled and the average sc-ar diameter on the lower three balls was determined. The results of these tests are set forth in the following table, in which the values for scar diameter are average values obtained from a number of test runs.

Table I.N0n-Addizive-Conmining Mineral Oil Scar diameter,

Load, kilograms: millimeters Table II.-Five Percent Solution of Di-n-Butyl Tin Sulfide in. Mineral Oil Scar diameter,

Load, kilograms: millimeters The results shown above clearly demonstrate the effectiveness of a lubricant composition of my invention as compared with a non-additive-containing mineral oil. As shown in Table II, a typical lubricant composition of my invention substantially reduced the average scar diameter through the load range of 2.5 to 40'kgs. Since the volume of material removed from the lower balls is proportional to the fourth power of the scar diameter, these results are quite striking in demonstrating the great superiority of my lubricant composition.

Other of the lubricant compositions set forth in Examples I through X were tested in the Four-Ball Wear Machine in the same manner as set forth above. The results of these tests are set forth in the following examples.

EXAMPLE XI A lubricant composition comprising 0.1 part of di-nbutyl tin sulfide admixed with 99.9 parts by weight of the mineral oil described in Example I was tested in the Four-Ball Wear Machine under the general conditions set forth above. The lubricant was subjected to a twohour test at a load of 2.5 kgs. Following the test the balls were disassembled and the average scar diameter on the lower three balls was found to be 0.30 millimeter.

EXAMPLE XII The lubricant composition of Example 11 comprising one part by weight of diisopropyl tin sulfide blended with 99 parts of a complex calcium base lubricating grease is tested in the Four-Ball Wear Machine for two hours with a load of kgs. under the general conditions set forth above. When so tested, the lubricant composition in Example ll will prove superior to the complex calcium base grease which forms the base material for the composition of Example II.

EXAMPLE XIV The lubricant composition of Example X was run in the Four-Ball Wear Machine for two hours at a load of 10 kgs. The average scar diameter was measured and found to be 0.57 millimeter.

The foregoing test results further demonstrate the superiority of my lubricating compositions as compared with non-additive-containing hydrocarbon oils and greases. These results further demonstrate that my lubricant compositions are extremely efiective at the relatively low additive concentration of 0.1 percent by weight as shown in Examples XI and XIV. The addition of 0.1 percent of di-n-butyl tin sulfide to the nonadditive-containing mineral oil described in Example I resulted in greatly reduced scar diameters as compared with the scar diameters set forth in Table I using the non-additive-containing oil.

A further series of tests was conducted to determine the effectiveness of my lubricants relative to non-additive hydrocarbon oils and greases. These tests were conducted in the El. tester in which the four balls were one-half inch in diameter and constructed of SAE 52- 100 steel. The upper ball was rotated at a speed of 1750 rpm. and the duration of each test run was one minute. The tests were conductedat room temperature.

To begin this test series, a number ofv tests were conducted to determine the lubricating effectiveness of a typical non-additive mineral oil. These test results were then used as a baseline for purposes of comparison with the results obtained when using my lubricants. The non-additive oil used is described inExample I and is the same oil used in obtaining the results set forth in Table 1. :Each of the values set forth in the table is an average value which was determined by a number of test runs.

Table H1.-N0n-Additive-Containing Mineral Oil Load, kilograms:

Scar diameter, millimeters The two average values for scar diameter obtained at a 40 kg. loading as set forth in Table Ill represent a sharp break in the wear-load curve. At this point, the slope of the curve is almost vertical. Thus, some test runs gave a low scar diameter at the 40 kg. loading while other test runs at the same loading gave a much higher value for scar diameter. The term weld indicated in Table ill for a kg. load denotes an extreme form of falure in which the upper ball actually welded to the lower three balls in less than one minute of testing due to the heat of friction generated, at the contacting surfaces.

' A further series of tests was conductedin the E.P. tester under the same test conditions used in establishing the data for Table Ill. as set forth in Example I and comprises a mixture of five parts by weight of di-n-butyl tin sulfide with parts of a typical non-additive mineral oil.

Table IV.-Five Percent Solution of Di-n-Bzltyl Tin Sulfide in Mineral Oil Load, kilograms: Scar diameter,

millimeters IQO 2.2

3.1 Weld The results set forth in Tables Ill and IV further indicate the effectiveness. of my lubricant compositions under the extreme loading conditions imposed by the EP. tester. As shown, the lubricant composition of the invention (Table IV) greatly reduced the scar diameter from that obtained with the non-additive mineral oil of Table III. Further, my lubricant composition made lubrication possible up to loads of 160 kgs. with Welding. In contrast, the non-additive lubricant failed entirely at loads of 90 kgs. as evidenced by welding of the upper ball to the stationary balls.

A further series of tests was'conducted in the El. tester in which the lubricant comprised 0.1 part by Weight of di-n-butyltin sulfide admixed with 99.9 parts of the mineral oil described in Example I. This same mineral oil was used in establishing the baseline data set forth in Table III. The conditions used in these tests were the same as those used in establishing the data for Tables Ill and 1V.

T able V.S0luti0n of 0 .1 Percent Di-n-Butyl Tin Sulfide in Mineral Oil Load, kilograms: Scar diameter,

The lubricant in these tests is.

am-mat The results set forth in Table V show the efiectiveness of my lubricant compositions with a low concentration of a specified dialkyl tin sulfide under the extreme loading conditions imposed by the E.P. tester. As shown by a comparsion of Table V with Table III, my lubricant composition proved far superior to the non-additive-containing mineral oil. This is manifested by a reduction in the average scar diameter over the entire load range and obtaining of effective lubrication up to 120 kgs. As noted in Table III, the non-additive mineral oil failed completely at a load of 90 kgs.

Other of the lubricant compositions set forth in Exampies I through X are improved lubricants when tested in the EP, tester. Thus, the lubricant composition of Example III comprising 0.1 part of di-n-hexyl tin sulfide in 99.9 parts of a phenol-treated, mixed-base mineral oil; the lubricant composition of Example IV comprising five parts of di-n-propyl tin sulfide and 95 parts of Mid Continent solvent-extracted, propanexlewaxed mineral oil, and the composition of Example VI comprising 005 part of n-butyl-n-hexyl tin sulfide in 99.95 parts of a complex lithium stearate-calcium stearate grease are improved lubricants in the EP. tester as compared with their re spective base lubricant compositions. Other lubricants which are improved in the El. tester with respect to their base compositions are a lubricant comprising four parts of sec-butyl 2-hexyl tin sulfide admixed with 96 parts of a solvent extracted Coastal oil having a viscosity index of 54, an aniline point of 989 C. and a Saybolt viscosity at 100 F. of 948 SUS, and a composition comprising ei ht parts of diisoamyl tin sulfide admixed with 92 parts of an aluminum-base lubricating grease consisting of 11 percent of aluminum stearate, 1 percent of lithium stearate and 88 percent of a mineral oil having a viscosity of 100 SUS at 100 F.

A further series of tests were conducted in the Four-Ball Wear Machine in which the balls were coated with a 0.001-inch thickness of pure gold. Gold is a relatively inert material and is therefore relatively unresponsive to a corrosion mechanism in forming a surface lubricant film on the gold surfaces. Thus, gold is not responsive to lubrication by additives. In these tests the balls were one-half inch in diameter. The upper ball was rotated at a speed of 79 rpm. and the lubricant under test was maintained at a temperature of 50 C.

EXAMPLE XV Two runs were made in the Four-Ball Wear Machine under the above conditions using a non-additive mineral oil as described in Example I as the lubricant. These tests were conducted at a load of 2.5 kgs. The average time to seizure based on the two runs was 71 minutes. Seizure was manifested by a stripping oif of the gold plate from its hard substrate and in formation of excessive wear debris.

EXAMPLE XVI Three tests were conducted in the Four-Ball Wear Machine under the general conditions set forth above. These tests were conducted at kgs. using as the lubricant a non-additive mineral oil having the characteristics set forth in Example I. The average time to seizure at the 5 kgs. loading was found to be minutes.

EXAMPLE XVII A lubricant composition comprising one part of lauric acid admixed with 99 parts of the non-additive mineral oil described in'Example I was tested in the gold-gold system under the general conditions set forth above. Seizure occurred in 0.25 minute at a load of 2.5 kgs.

EXAMPLE XVIII The lubricant composition tested in Example XVII was tested in the gold-gold system at a loading of 5 kgs.

It) under the above conditions. taneously.

Seizure occurred instan' EXAMPLE XIX A lubricant composition comprising one part of a leadnaphthenate soap in 99 parts of the mineral oil described in Example I was tested in the Four-Ball Wear Machine under the general test conditions set forth above. At a load of 5 kilograms, seizure occurred instantaneously, and the gold plating was rapidly stripped from the ball surfaces.

EXAMPLE XX A lubricant composition comprising 1 part of tricresylphosphate in 99 parts of the mineral oil described in Example I was tested in the Four-Ball Wear Machine under the general conditions set forth above. At a load of 2.5 kgs. seizure occurred in 32 minutes. At the higher load of 5 kgs., seizure occurred in 7.8 minutes.

EXAMPLE XXI A lubricant composition comprising five parts of carbon tetrachloride admixed with parts by weight of the non-additive mineral oil described in Example I was tested at loads of 2.5 and 5 kgs. under the above conditions. Seizure occurred in 88 minutes at the 2.5 kg. load and in 51 minutes at the 5 kg. load.

EXAMPLE XXII The lubricant composition of Example I comprising five parts by weight of di-n-butyl tin sulfide admixed with 95 parts of a non-additive mineral oil was tested at loads of 2.5 and 5 kgs. under the general conditions set forth above. In each of the tests effective lubrication of the gold-plated balls was obtained for minutes without seizure. The tests were terminated without failure.

EXAMPLE XXIII The lubricant composition of Example I was tested in the Four-Ball Wear Machine under the identical conditions used in Example XXII with a 5 kg. load. The test was run for 14.3 hours before seizure occurred.

The above test data is significant in demonstrating the effectiveness of my lubricant compositions in applications where conventional E.P. type additives are ineffective. As shown in Examples XV through XXI, conventional E.P. additives, such as lauric acid, tricresylphosphate, carbon tetrachloride, and lead soap, are ineffective in improving the lubricating properties of mineral oil when lubricating an inert material, such as gold. In fact,

the addition of the E.P. additive in some cases appearedresults of Example XXIII demonstrate an increase in lu-- bricating effectiveness, as compared with the results of Examples XV through XXI, which is in excess of 400- fold. These results not only show a phenomenal improvement in lubricating effectiveness achieved by my lubricant compositions, but further show the unique nature by which my lubricants function. Since the conventional E.P. additives of Examples XV through XXI were ineffective, the mechanism by which my lubricants function is clearly more than a simple corrosion mechanism. This mechanism is, as defined hereinbefore, thought to be in the nature of film formation. The film formation is believed to occur due to the thermal degradation of certain dialkyl tin sulfide additives to form a thin lubricating film on the lubricating surfaces. This mechanism, not deenvy r51 lithium stearate-calcium stearate grease; and the compo- 1Q sition of Example'IV comprising five parts of di-n-propyl tin sulfide and 95 parts of Mid-Continent, solvent-extracted, propane-dewaxed mineral oil are very effective in lubricating gold-plated balls in the Four-Ball Wear Machine. Other lubricating compositions such as for example a composition comprising nine parts of isopropyl isoamyl tin sulfide admixed with 91 parts of a conventionally refined Coastal oil having a viscosity of 222 SUS at 100 F. and 44.0 SUS at 210 F, a viscosity index of 19, a flash point of 350 F. and a tire point of 385 F., and a composition comprising two parts of di-sec-butyl tin sulfide admixed with 98 parts of a Mid-Continent bright stock having a Saybolt viscosity of 3370 SUS at 100 F. and 156-4 SUS at 210 F., a viscosity index of 77, a flash point of 530 F, a fire point of 610 F. and a pour point of F., are more effective than their respective base oil compositions when tested in the Four-Ball Wear Machine in the above manner.

My lubricating compositions are useful in lubricating a large variety of surfaces. Thus, my compositions will improve the lubrication of suchdiverse metals as gold, titanium, copper and silver. In addition, plastics, such as nylon, polyvinyl chloride, polyethylene and the like, are also lubricated by my compositions. Also, hard, inert, inorganic, refractory-like ceramics may be lubricated by my compositions. Examples of such materials are aluminum oxide, tungsten carbide, titanium carbide, glass and the like.

My lubricating compositions function effectively over a wide temperature range. To demonstrate this facility, three tests were conducted in the Four-Ball Wear Machine using one-half inch diameter balls constructed of SAE 52-100 steel. The upper ball was rotated at a speed of 570 rpm. at a loading of 40 kgs. and each run was conducted for two hours. The results obtained are set forth in the following examples.

EXAMPLE XXIV A lubricant composition comprising five parts by weight of di-n-butyl tin sulfide in a non-additive mineral oil as described in Example I'WaS run in the Four-Ball Wear Machine under the general conditions set forth above at a temperature of C. Following the run, the average scar diameter was measured as 0.79 millimeter. The volume of material removed from the lower three stationary balls was 228x10- cubic millimeters. The average volume of material removed from each stationary ball was 76 10 cubic millimeters. The non-additive mineral oil described in Example I, when tested under the same conditions, gave a scar diameter of 0.86 millimeter. The total volume of metal removed from the three stationary balls was 315 10- cubic millimeters and the volume of metal from each stationary ball was 105 10- cubic millimeters.

EXAMPLE XXV The lubricant composition of Example I comprising five parts of di-n-butyl tin sulfide in a non-additive mineral oil was run in the Four-Ball Wear Machine at a temperature of 70 C. under the above conditions. The average scar diameter on the lower three balls was 0.6 millimeter. This resulted in 78 10 cubic millimeters of metal being removed from the stationary balls or an average value per ball of 26x10 cubic millimeters. When tested under the same conditions, a non-additive mineral oil as described in Example I gave a scar diameter of 0.84 millimeter and 294 lO- cubic millimeters of metal removed rom the stationary balls. The average amount of metal removed per stationary ball was 98x10 cubic millimeters.

EXAMPLE XXVI The lubricant composition of Example I was tested in the Four-Ball Wear Machine at a temperature of 143 C. under the above test conditions. The average scar diameter on the lower three balls following the test run was 0.84 millimeter. The total volume of metal removed from the three stationary balls was 282x 10"* cubic millimeters or 94x10 cubic millimeters per ball. The nonadditive base oil described in Example I, when tested under the same conditions, gave an average scar diameter of 0.99 millimeter. The total volume amount of metal removed was 555 l0 cubic millimeters or l l0* cubic millimeters per stationary specimen.

Results of Examples XXIV through XXVI clearly demonstrate the effectiveness of a lubricant composition of my invention over a wide temperature range in comparison with a typical non-additive mineral oil. As shown, my lubricant composition was more effective than the nonadditive oil at temperatures ranging from 50 C. to 143 C. Since modern lubricants are used over a wide range of operating temperatures, these results are significant in demonstrating that my compositions are effective over the temperature range in which commercial lubricants must function.

' As stated hereinbefore, 11y fluid compositions have great utility as cutting oils. In formulating these compositions, the dialkyl tin sulfide compound in which each alkyl group contains from three to six carbon atoms is generally present in a concentration between about 10 percent to about 95 percent by weight. A particularly preferred cutting oil is one containing from about 10 to about 95 percent by weight of di-n-butyl tin sulfide. This composition is found to provide an extremely effective cutting oil when used over a wide operating range of temperatures and pressures.

In formulating my cutting oils, the base material is a hydrocarbon oil having a viscosity at F. of from about 50 to about 500 SUS. Variations from these values will be permissible, depending on the use to which the cutting oil will be put. For example, it is generally desirable to use a less viscous base oil in forming a cutting oil to be used for a high-speed, continuous machining operation. For most cutting operations, it is preferable that the base oil have a viscosity from about 100 to about 250 SUS at 100 F.

To further illustrate cutting oil formulations within the scope of my invention, there are the following examples in which all parts and percentages are on a weight basis, unless otherwise indicated.

EXAMPLE XXVI! Pennsylvania neutral oil (185 SUS at 100 F.) containing 10 percent of di-n-butyl tin sulfide.

EXAMPLE xxxvm Mid-Continent neutral mineral oil (290 SUS at 100 F.) containing 50 percent of diisopropyl tin sulfide.

EXAMPLE XXIX California neutral mineral oil (382 SUS at 100 F.) containing 95 percent of di-n-propyl tin sulfide.

EXAMPLE XXX Solvent-extracted parafiinic mineral oil SUS at 100 F.) containing 80 percent of di-n-hexyl tin sulfide.

EXAMPLE XXXI Coastal neutral solvent-extracted mineral oil (311 SUS at 100 F.) containing 40 percent of n-butyl-n-hexyl tin sulfide.

The results set forth in Table V show the effectiveness of my lubricant compositions with a low concentration of a specified dialkyl tin sulfide under the extreme loading conditions imposed by the E.P. tester. As shown by a comparsion of Table V with Table III, my lubricant composition proved far superior to the non-additive-containing mineral oil. This is manifested by a reduction in the average scar diameter over the entire load range and obtaining of effective lubrication up to 120 kgs. As noted in Table III, the non-additive mineral oil failed completely at a load of 90 kgs.

Other of the lubricant compositions set forth in Exampics I through X are improved lubricants when tested in the El. tester. Thus, the lubricant composition of Example III comprising 0.1 part of di-n-hexyl tin sulfide in 99.9 parts of a phenol-treated, mixed-base mineral oil; the lubricant composition of Example IV comprising five parts of di-n-propyl tin sulfide and 95 parts of Mid- Continent solvent-extracted, propane-dewaxed mineral oil, and the composition of Example VI comprising 0. part of n-butyl-n-hexyl tin sulfide in 99.95 parts of a complex lithium stearate-calcium stearate grease are improved lubricants in the EP. tester as compared with their respective base lubricant compositions. Other lubricants which are improved in the ER tester with respect to their base compositions are a lubricant comprising four parts of sec-butyl 2-hexyl tin sulfide admixed with 96 parts, of a solvent extracted Coastal oil having a viscosity index of 54, an aniline point of 989 C. and a Saybolt viscosity at 100 F. of 948 SUS, and a composition comprising eight parts of diisoamyl tin sulfide admixed with 92 parts of an aluminum-base lubricating grease consisting of 11 percent of aluminum stearate, 1 percent of lithium stearate and 88 percent of a mineral oil having a viscosity of 100 SUS at 100 F.

A further series of tests were conducted in the Four-Ball Wear Machine in which the balls were coated with a 0.00l-inch thickness of pure gold. Gold is a relatively inert material and is therefore relatively unresponsive to a corrosion mechanism in forming a surface lubricant film on the gold surfaces. Thus, gold is not responsive to lubrication by El. additives. In these tests the balls were one-half inch in diameter. The upper ball was rotated at a speed of 79 rpm. and the lubricant under test was maintained at a temperature of 50 C.

EXAMPLE XV Two runs were made in the Four-Ball Wear Machine under the above conditions using a non-additive mineral oil as described in Example I as the lubricant. These tests were conducted at a load of 2.5 kgs. The average time to seizure based on the two runs was 71 minutes. Seizure was manifested by a stripping off of the gold plate from its hard substrate and in formation of excessive wear debris.

EXAMPLE XVI Three tests were conducted in the Four-Ball Wear Machine under the general conditions set forth above. These tests were conducted at 5 kgs. using as the lubricant a non-additive mineral oil having the characteristics set forth in Example I. The average time to seizure at the 5 kgs. loading was found to be 20 minutes.

EXAMPLE XVII A lubricant composition comprising one part of lauric acid admixed with 99 parts of the non-additive mineral oil described in Example I was tested in the gold-gold system under the general conditions set forth above. Seizure occurred in 0.25 minute at a load of 2.5 kgs.

' EXAMPLE XVIII The lubricant composition tested in Example XVII Was tested in the gold-gold system at a loading of 5 kgs.

m to

10 under the above conditions. taneously.

Seizure occurred instan- EXAMPLE XIX A lubricant composition comprising one part of a leadnaphthenate soap in 99 parts of the mineral oil described in Example I was tested in the Four-Ball Wear Machine under the general test conditions set forth above. At a load of 5 kilograms, seizure occurred instantaneously, and the gold plating was rapidly stripped from the ball surfaces.

EXAMPLE XX A lubricant composition comprising 1 part of tricresylphosphate in 99 parts of the mineral oil described in Example I was tested in the Four-Ball Wear Machine under the general conditions set forth above. At a load of 2.5 kgs. seizure occurred in 32 minutes. At the higher load of 5 kgs., seizure occurred in 7.8 minutes.

EXAMPLE XXI A lubricant composition comprising five parts of carbon tetrachloride admixed with parts by weight of the non-additive mineral oil described in Example I was tested at loads of 2.5 and 5 kgs. under the above conditions. Seizure occurred in 88 minutes at the 2.5 kg. load and in 51 minutes at the 5 kg. load.

EXAMPLE XXII EXAMPLE XXIII The lubricant composition of Example I was tested in the Four-Ball Wear Machine under the identical conditions used in Example XXII with a 5 kg. load. The test was run for 14.3 hours before seizure occurred.

The above test data is significant in demonstrating the effectiveness of my lubricant compositions in applications where conventional E.P. type additives are inelfective. As shown in Examples XV through XXI, conventional E.P. additives, such as lauric acid, tricresylphosphatc, carbon tetrachloride, and lead soap, are ineffective in improving the lubricating properties of mineral oil when lubricating an inert material, such as gold. In fact, the addition of the E.P. additive in some cases appeared to lessen the lubricating effectiveness of the non-additive mineral oil.

In contrast, a lubricating composition of my invention as set forth in Examples XXII and XXIII provided extremely effective lubrication. The tests set forth in Example XXII were terminated Without failure of the gold plate following two-hour runs at loads of 2.5 and 5 kgs. In Example XXIII lubrication was obtained for the phenomenal time of 14.3 hours before failure occurred. The results of Example XXIII demonstrate an increase in lubricating effectiveness, as compared with the results of Examples XV through XXI, which is in excess of 400- fold. These results not only show a phenomenal improvement in lubricating efiectiveness achieved by my lubricant compositions, but further show the unique nature by which my lubricants function. Since the conventional E.I. additives of Examples XV through XXI were ineffective, the mechanism by which my lubricants function is clearly more than a simple corrosion mechanism. This mechanism is, as defined hereinbefore, thought to be in the nature of film formation. The film formation is believed to occur due to the thermal degradation of certain dialkyl tin sulfide additives to form a thin lubricating film on the lubricating surfaces. This mechanism, not dependent on a corrosion mechanism, operates substantially tracted, propane-dewaxed mineral oil are very effective in lubricating gold-plated balls in the Four-Ball Wear Machine. Other lubricating compositions such as for example a composition comprising nine parts of isopropyl isoamyl tin sulfide admixed with 91 parts of a conventionally refined Coastal oil having a viscosity of 222 SUS at 100 F. and 44.0 SUS at 210 F, a viscosity index of 19, a flash point of 350 F. and a this point of385 E, and a composition comprising two parts of di-sec-butyl tin sulfide admixed with 98 parts of a Mid-Continent bright stock having a Saybolt viscosity of 3370 SUS at 100 F. and 156.4 SUS at 210 F., a viscosity index of 77, a flash point of 530 F., a fire point of 610 F. and a pour point of 25 F., are more effective than their respective base oil compositions when tested in the Four-Ball Wear Machine in the above manner.

My lubricating compositions are useful in lubricating a large variety of surfaces. Thus, my compositions will improve the lubrication of such diverse metals as gold, titanium, copper and silver. In addition, plastics, such as nylon, polyvinyl chloride, polyethylene and the like, are also lubricated by my compositions. Also, hard, inert, inorganic, refractory-like ceramics may be lubricated by my compositions. Examples of such materials are aluminum oxide, tungsten carbide, titanium carbide, glass and the like.

My lubricating compositions function effectively over a wide temperature range. T demonstrate this facility, three tests were conducted in the Four-Ball Wear Machine using one-half inch diameter balls constructed of SAE 52-100 steel, The upper ball was rotated at a speed of 570 r.p.m. at a loading of 40 kgs. and each run was conducted for two hours. The results obtained are set "forth in the following examples.

EXAMPLE XXlV A lubricant composition comprising five parts by weight of di-n-butyl tin sulfide in a non-additive mineral oil as described in Example I was run in the Four-Ball Wear Machine under the general conditions set forth above at a temperature of 50 C. Following the run, the average scar diameter was measured as 0.79 millimeter. The volume of material removed from the lower three stationary balls was 228 X cubic millimeters. The average volume of material removed from each stationary ball was 76 10 cubic millimeters. The non-additive mineral oil described in Example I, when tested under the same conditions, gave a scar diameter of 0.86 millimeter. The total volume of metal removed from the three stationary balls was 315x10- cubic millimeters and the volume of metal from each stationary ball was 105 X 10 cubic millimeters.

EXAMPLE XXV The lubricant composition of Example I comprising five parts of di-n-butyl tin sulfide in a non-additive mineral oil was run in the Four-Ball Wear Machine at a temperature of 70 C. under the above conditions. The average scar diameter on the lower three balls was 0.6 millimeter. This resulted in 78 X10 cubic millimeters of metal being removed from the stationary balls or an average value per ball of 26 10 cubic millimeters. When tested under the same conditions, a non-additive mineral oil as described in Example I gave a scar diameter of 0.84 milli- 12 meter and 294x 10* cubic millimeters of metal removed from the stationary balls. The average amount of metal removed per stationary ball was 98 10- cubic millimeters.

EXAMPLE XXVI The lubricant composition of Example I was tested in the Four-Ball Wear Machine at a temperature of 143 C. under the above test conditions. The average scar diameter on the lower three balls following the test run was 0.84 millimeter. The total volume of metal removed from the three stationary balls was 282 10- cubic millimeters or 94X 10* cubic millimeters per ball. additive base oil described in Example I, when tested under the same conditions, gave an average scar diameter of 0.99 millimeter. The total volume amount of metal removed was 555 10- cubic millimeters or 185x10 cubic millimeters per stationary specimen.

Results of Examples XXIV through XXVI clearly demonstrate the eifectiveness of a lubricant composition of my invention over a wide temperature range in comparison with a typical non-additive mineral oil. As shown, my lubricant composition was more effective than the nonadditive oil at temperatures ranging from 50 C. to 143 C. Since modern lubricants are used over a wide range of operating temperatures, these results are significant in demonstrating that my compositions are effective over the temperature range in which commercial lubricants must function.

As stated hereinbefore, my fluid compositions have great utility as cutting oils. In formulating these compositions, the dialkyl tin sulfide compound in which each alkyl group contains from three to six carbon atoms is generally present in a concentration between about 10 percent to about 95 percent by weight. A particularly preferred cutting oil is one containing from about 10 to about 95 percent by weight of di-n-butyl tin sulfide. This composition is found to provide an extremely effective cutting oil when used over a wide operating range of temperatures and pressures.

In formulating my cuttin oils, the base material is a hydrocarbon oil having a viscosity at F. of from about 50 to about 500 SUS. Variations from these values will be permissible, depending on the use to which the cutting oil will be put. For example, it is generally desirable to use a less viscous base oil in forming a cutting oil to be used for a high-speed, continuous machining operation. For most cutting operations, it is preferable that the base oil hage a viscosity from about 100 to about 250 SUS at 100 To further illustrate cutting oil formulations within the scope of my invention, there are the following examples in which all parts and percentages are on a weight basis, unless otherwise indicated.

EXAMPLE XXVII Pennsylvania neutral oil (185 SUS at 100 F.) containing 10 percent of di-n-butyl tin sulfide.

EXAMPLE XXXVIII Mid-Continent neutral mineral oil (290 SUS at 100 F.) containing 50 percent of diisopropyl tin sulfide.

EXAMPLE XXIX California neutral mineral oil (382 SUS at 100 F.) containing 95 percent of di-n-propyl tin sulfide.

EXAMPLE XXX Solvent-extracted parafiinic mineral oil SUS at 100 F.) containing 80 percent of di-n-hexyl tin sulfide.

EXAMPLE, XXXI Coastal neutral solvent-extracted mineral oil (311 SUS at 100 F.) containing 40 percent of n-butyl-n-hexyl tin sulfide.

The nonis EXAMPLE XXXII Solvent-extracted Pennsylvania bright stock (500 SUS at 100 F.) containing 73 percent of di-n-pentyl tin sulfide.

EXAMPLE XXXHI Polybutene oil (537 SUS at 100 F.) containing 87 percent of di-n-butyl tin sulfide.

EXAMPLE may Conventionally-refined Pennsylvania neutral mineral oil (99 SUS at 100 F.) containing 38 percent of di-nbutyl tin sulfide.

A number of tests were run to determine the effectiveness of my compositions, as in Examples XXVH through XXXTV, as cutting oils. These tests were generally of two types. The first type was carried out on a milling machine with a high-speed tool (rake angle: 15"; clearance angle: The cutting tool was constructed of 18-4-1 steel which contains 18 percent of tungsten, 4 percent of chromium and 1 percent of vanadium. The work material was constructed of SAE 1018 steel. The length of the test specimen in the direction of the cut was two inches and its width in the direction parallel to the cutting edge was 0.25 inch. A constant depth of 0.015 inch and a cutting speed of 12.25 inches per minute were used in all the tests.

A newly-ground tool tip was used for each test. The chip that was formed during the first cut was discarded to eliminate any contamination originally on the tool surface and to allow conditions to reach an equilibrium state. Whenever backing of the tool to the starting point was necessary, the tool was raised to prevent it from dragging over the cut surface.

One criterion for determining the effectiveness of the cutting oil in this test is the length of the metal chip obtained with various cutting oil formulations. The chip ength is directly proportional to the effectiveness of the boundary lubrication during cutting and hence is proportional to the effectiness of the cutting oil. A second criterion is the quality of the surface finish as determined by visual inspection of the test specimen upon completion of the cutting operation. The results of these tests are set forth in the following examples.

EXAMPLE XXX V A commercial mineral cutting oil was tested under the conditions set forth above. This oil has a viscosity at 100 F. of from 90 to 110 SUS and is commonly used in light machining operations. The chip length resulting from the test was from 0.73 to 0.76 inch. The surface finish of the work piece was relatively poor in that the surface was checked from the cutting tool.

EXAMPLE XXXVI A cutting oil composition comprising ten parts of di-nbutyl tin sulfide admixed with 90 parts of the cutting oil of Example XXXV was tested in the manner set forth above. The chip length obtained from the test was 0.92 inch in length. The surface condition of the work piece in this test was exceptionally good with the surface being smooth and free from any check marks.

Other of the compositions of my invention give superior results as cutting oils. Thus, for example, cutting oil compositions comprising Pennsylvania neutral mineral oil (185 SUS at 100 F.) admixed with 15 parts by weight of diisopropyl tin sulfide; a solvent-extracted Pennsylvania bright stock (500 SUS at 100 F.) admixed with 50 parts by weight of di-n-hexyl tin sulfide; a conventionally-refined Pennsylvania neutral oil (99 SUS at 100 F.) admixed with 95 parts of di-n-butyl tin sulfide and a conventionally-refined Coastal oil (440 SUS at 100 F.) containing 75 percent by wei ht of di-n-pentyl tin sulfide likewise are superior cutting oils as compared with their respective non-additive base oils.

A further series of tests was performed to determine the effectiveness of my compositions as cutting oils. These tests involved the use of a plate constructed of 304 stainless steel and having a thickness of three-fourths of an inch. A plurality of holes were drilled in the plate with a No. 7 drill after which the holes were tapped with a one-fourth inch outside diameter tap having 20 threads per inch. The holes were tapped to a depth of five-eighths of an inch which left one-eighth of an inch of the hole untapped. The speed of rotation of the tapping tool was 267 r.p.m. The cutting oil was placed at the contact point between the tool and work piece by either of two methods. In the first method, the oil was spread evenly over the interior surface of the drilled hole prior to the tapping operation. In the other method, oil was poured against the surface of the tapping tool during the tapping operation. The manner in which the cutting oil was placed between the tool and cut surface proved to be immaterial to the cutting oils etfectiveness.

One criterion for determining the effectiveness of the cutting fluid in this test is the number of holes which can be tapped before the tapping tool is broken. As'the effectiveness of the cutting oil is increased, the number of holes which can be successfully tapped with a single tool are increased in a proportionate amount. Another criterion for the lubricating etfectiveness is the ease of the tapping operation. If the cutting oil is effective, the tap turns in a smooth continuous manner. If the oil is not effective, the movement of the tap will not be smooth but will be jerky. A further criterion for effectiveness is the ability of the oil to furnish etfective lubrication without smoking. A manifestation of faulty operation is the eneration of heat between the tap and the metal being cut, which in turn causes oxidation of the oil and the emission of smoke. Thus, if no smoke is emitted, the amount of heat generated is of low degree. The following examples set forth the results obtained from the tests.

EXAMPLE XXXVIII A commercial cutting oil having a viscosity of to SUS at 100 F., a total sulfur content of 2.5 percent minimum, a total chlorine content of 0.6 percent minimum and containing 0.5 percent of saponifiable matter was tested in the manner set forth above. Three tests were conducted. The tapping tool broke during tapping of the first hole in the first and second tests. In the third test the tapping tool broke during the third tapping. Thus, the largest number of holes tapped on any single test was two in the third test and in two out of the three tests failure occurred during the tapping of the first hole.

EXAMPLE XXXIX A cutting oil comprising 95 parts of the cutting fluid described in Example XXXVIII admixed with five parts of di-n-butyl tin sulfide was tested as a cutting fluid in exactly the same manner as in Example XXXVIII. In this test 30 holes were tapped successfully without failure of the tapping tool. The test was then terminated with the tapping tool showing no sign of excessive wear. During the tapping operation, there was no sign of smoke. Also, the movement of the tapping tool was sm oth and steady, thus indicating an even cutting operation.

The above test results demonstrate the superiority of my compositions as cutting oils.- In Example XXXIX, the effectiveness of the cutting Oil was in excess of 15 times that of the best test run of Example XXXVHI.

This is truly a remarkable improvement which enables fide; the composition of Example XXX comprising 20 percent of a solvent-extracted parafiinic mineral oil (155 SUS at 100 F.) and 80 percent of di-n-hexyl tin sulfide, and the composition of Example XXXH comprising 27 percent of a solvent-extracted Pennsylvania bright stock (500 SUS at 100 F.) and 73 percent of di-n-pentyl tin sulfide provide improved cutting oils when compared with their respective base oils in the tapping test set forth above.

My compositions can be used in cutting a variety f materials. Thus, such diverse materials as stainless steel, titanium, brass, polymethylmethacrylate, polyvinylchloricle and cast iron may be cut smoothly when utilizing my compositions as cutting fluids.

As set forth hereinbefore, my compositions are multifunctional in that they are not only good lubricants and cutting oils but are also extremely oxidatively stable. In order to demonstrate the oxidative stability of my compositions, they were tested in the Polyveriform Oxidation Stability Test as described in the paper entitled Factors Causing Lubricating Oil Deterioration in Engines, Ind. and Eng. Chem., Anal. Ed. 17, 302 (1945). This test effectively evaluates the performance of lubrieating oil antioxidants. The test equipment procedure employed and correlations of the results with engine performance are discussed in the paper cited above.

My test procedure employs a slight modification from that set forth in the publication in that it does not employ the steel sleeve and copper test piece there described. The test conditions involved the passing of 48 liters of air per hour through the composition under test for a total period of 20 hours. The composition is maintained at a temperature of 300 F. during this period. Oxidative deterioration of the test composition was promoted by employing oil soluble oxidation catalysts. These catalysts comprised 0.05 percent by weight of ferric oxide, as ferric Z-ethylhexoate, and 0.10 percent by weight of lead bromide dissolved in the composition being tested. Following the tests the amount of oxidation of the test composition was determined by 2 factors:

(1) The increase in the viscosity of the test composi tion as measured at 100 F. This increase is expressed in the form of a percent increase. This is a ratio, expressed as a percentage, of the increase in the viscosity of the test composition divided by the viscosity of the composition prior to testing.

(2) The acid number of the test composition after testing. The acid number is the number of milligrams of potassium hydroxide required to neutralize one gram of the test composition.

EXAMPLE XL The base oil comprising a Mid-Continent, chlo-rex solvent-extracted, propane-dewaxed mineral oil was tested in the polyveriform test under the conditions set forth above. The sulphur content of the base oil was 0.17 percent and the flash point (ASTM D 92) Was 405 F. The viscosity at 100 F. was 233 Saybolt Universal seconds. Following the test, the acid number was found to be 5.6, and the percent viscosity increase was 131.

EXAMPLE XLI A composition of my invention comprising one percent by weight of di-n-butyl tin sulfide in the base oil used in Example XL was tested in the polyveriform tester under the conditions set forth above. After testing, the acid number of the composition was 2.5, and the percent viscosity increase was 14.

EXAMPLE XLII A composition comprising 0.5 Weight percent of di-nbutyl tin sulfide in the base oil used in Example XL was tested in the polyveriform tester under the identical it? conditions used in Example XL. After testing, the acic number was 5.2, and the percent viscosity increase was 5 As shown by the test data set forth in Examples L through XLll, the compositions of my invention are much more oxidatively stable than the nomadditive conta base oil used in their formulation. As shown in Examples XLI and XLil, the presence of 1.0 and 0.5 percent of di-n-butyl tin sulfide in the base oil resulted in decreased acid numbers, and a lower percent viscosity increase than that obtained by the base oil. Sin e these values are a direct measure of the oxidation of the oil, they show that my compositions are much more oxidatively stable than the base oil.

Other of my compositions show increased oxidative stability as compared with base oil when subjected t the polyveriform test. Thus, the composition of Example ill comprises 99.9 parts of a phenol-treated, mixedbase mineral oil, and 0.1 part of di-n-hexyl tin sulfide; the composition of Example IV comprising 5 parts f di-n-propyl tin sulfide in parts of Mid-Continent, solvent-extracted, propane-dewaxed mineral oil; the con1position of Example XXXI comprising 60 percent of a Coastal neutral, solvent-extracted mineral oil and 40 percent of n-butyl-n-hexyl tin sulfide; and the composition of Example XXlX comprising 95 percent of di-n-propyl tin sulfide admixed with 5 percent of a California neutral mineral oil are more oxidatively stable than their respective base oils when subjected to the polyveriform test.

In order to further illustrate the oxidative stability of my compositions, they were subjected to the Panel Coker Test. This test is described in the Aeronautical Standards of the Departments of Navy and Air Force, Spec, MIL- L-7808C, dated November 2, 1955. The Panel Coker apparatus was operated at 550 F. for 10 hours on a cycling schedule with the splasher being in operation for five seconds followed by a quiescent period of 55 seconds. On completion of these tests, the extent to which the test oil had decomposed was determined by weighing the amount of deposits formed on the metallic panel. The test results are set forth by the following.

EXAMPLE XLIH A non-additive-containing Mid-Continent, chlorex solvent-extracted, propane-dewaxed mineral oil as described in Example XL was tested in the Panel Coker Test under the above conditions. Following the test, the panel was weighed, and the amount of deposit formed was determined to be 434 milligrams.

EXAMPLE XLIV A composition of my invention comprisin 0.5 percent by weight of di-n-butyl tin sulfide admixed with the mineral oil used in Example XLilI was tested in the Panel Coker under the above conditions. On completion of the test, the panel was weighed. Only 13 milligrams of deposit had been formed. 7

The results set forth in Examples XLIH and XLlV further demonstrate the great increase in oxidative stability achieved by a composition of my invention as compared with a non-additive base oil. As shown, the deposit resulting from my composition (Example XLEV) was 13 milligrams, whereas the deposit from the base oil (Example XLIII) was 434 milligrams. Thus, in terms of the Panel Coker Test, my composition was approximately 33 times more effective than the non-additive base oil.

Other of my compositions show greatly improved oxidation characteristics as compared with base oil in the Panel Coker Test. Thus, the composition of Example V comprising 4 parts of di-n-pentyl tin sulfide in 96 parts of a solvent-extracted, Pennsylvania bright stock; the composition of Example XXVIII comprising 50 percent by weight of diisopropyl tin sulfide in a Mid-Continent neutral mineral oil, and the composition of Example 37 XXX comprising a solvent-extracted parafiinic mineral oil containing 80 percent by weight of di-n-hexyl tin sulfide show improved oxidative stability in the Panel Coker Test as compared with their respective base oils.

The many examples in this specification of lubricant and cutting oil compositions, and test data are by way of illustration only and should not be construed as limiting the scope of my invention. Obvious variations within the scope of the invention will be readily apparent to one skilled in the art. An example would be in the use of a plurality of the specified di-alkyltin sulfide compounds set forth above as additives to a single hydrocarbon base lubricant. Another example would be in varying the cutting tool speed, cutting oil composition, cutting tool composition, and work piece composition from those set forth in the examples.

My compositions may contain other compounds such as conventional soaps, antioxidants, thickeners or additives which are present in commercial hydrocarbon base lubricants and cutting oils since such additives in no way inhibit the effectiveness of my compositions. Further, my compositions may be used as lubricants or cutting oils for a wide variety of materials and find application in the lubrication and cutting of such diverse materials as tungsten carbide, titanium, glass, polyvinylchloride, steel, gold, polyethylene, aluminum oxide, and nylon.

My compositions have great utility in lubricating electrically conductive noble metal lubricating systems such as for example, silver-silver or silver-graphite contacts founds in electrical switches, motors, relays and electrical generating equipment. The lubricant films laid down by my compositions have high electrical conductivity and therefore, would not inhibit the transfer of electric current between the lubricated members.

Having set forth and described the invention fully by way of the foregoing examples and explanation, I desire to be limited only by the scope of the following claims.

I claim:

1. A hydrocarbon base lubricant having admixed therewith from about 0.05 percent to about 95 percent by weight of a compound having the formula Sn: S

in which R and R are alkyl groups containing from three to six carbon atoms, inclusive.

2. A hydrocarbon base lubricant having admixed therewith, in an amount between about 0.05 to about 10 percent by weight, a di-alkyltin sulfide compound having the formula /Sn=S R2 in which R and R are alkyl groups containing from three to six carbon atoms, inclusive.

3. The lubricant composition of claim 2 wherein the di-alkyltin sulfide compound is di-n-butyltin sulfide.

4. A hydrocarbon cutting oil having admixed therewith from about 10 percent to about percent by weight of a di-alkyltin sulfide compound having the formula in which R and R are alkyl groups containing from three to six carbon atoms, inclusive.

References fitted in the file of this patent UNITED STATES PATENTS Lincoln June 30, 1942 Fawcett June 13, 1950 Weinberg et a1. Apr. 16, 1957 

1. A HYDROCARBON BASE LUBRICANT HAVING ADMIXED THEREWITH FROM ABOUT 0.05 PERCENT TO ABOUT 95 PERCENT BY WEIGHT OF A COMPOUND HAVING THE FORMULA 